Rcapture (version 1.2-1)

descriptive: Descriptive Statistics

Description

This function produces descriptive statistics for capture-recapture data.

Usage

descriptive(X, dfreq=FALSE, dtype=c("hist","nbcap"), t)

## S3 method for class 'descriptive':
print(x, \dots)

## S3 method for class 'descriptive':
plot(x, main="Exploratory Heterogeneity Graph", \dots)

Arguments

X

The matrix of the observed capture histories (see Rcapture-package for a description of the accepted formats).

dfreq

A logical. By default FALSE, which means that X has one row per unit. If TRUE, it indicates that the matrix X contains frequencies in its last column.

dtype

A characters string, either "hist" or "nbcap", to specify the type of data. "hist", the default, means that X contains complete observed capture histories. "nbcap" means that X contains numbers of captures (see

t

Requested only if dtype="nbcap". A numeric specifying the total number of capture occasions in the experiment.

x

An object, produced by the descriptive function, to print or to plot.

main

A main title for the plot

...

Further arguments to be passed to methods (see print.default and plot.default).

Value

• n
  The total number of captured units.
• base.freq
  A table of basic descriptive statistics. For $i=1,\ldots,t$ : fi: the number of units captured $i$ times ui: the number of units captured for the first time on occasion $i$ vi: the number of units captured for the last time on occasion $i$ ni: the number of units captured on occasion $i$
• m.array
  A $t$ by $t$ matrix containing recapture statistics for units released on occasion $i$, for $i=1,\ldots,t$ : ni: the number of units released on occasion $i$; c2: the number of units released on occasion $i$ and recaptured for the first time on occasion 2; ... ct: the number of units released on occasion $i$ and recaptured for the first time on occasion $t$; not recapt: the number of units released on occasion $i$ and never recaptured again. The m.array matrix is used in Mark (see White and Burnham 1999; White 2005) and MSurge (see Choquet, Reboulet, Pradel, Gimenez, and Lebreton 2004) to fit open population models to the data.

Details

The plot.descriptive function produces an exploratory heterogeneity graph. In the absence of heterogeneity, the relation(s) presented in the graph should be almost linear. Convex fonctions indicate heterogeneity. If dtype="nbcap", only the the number of units captured $i$ times, fi, can be computed.

References

Baillargeon, S. and Rivest, L.P. (2007) Rcapture: Loglinear models for capture-recapture in R. Journal of Statistical Software, 19(5), http://www.jstatsoft.org/v19/i05. Choquet, R., Reboulet, A.M., Pradel, R., Gimenez, O. and Lebreton, J.D. (2004). M-Surge: New Software Specifically Designed for Multistate Capture-Recapture Models. Animal Biodiversity and Conservation, 27.1, 207--215. Lindsay, B. G. (1986) Exponential family mixture models (with least-squares estimators). Annals of Statistics, 14, 124--137. Rivest, L.P. (2008) Why a time effect often has a limited impact on capture-recapture estimates in closed populations. Canadian Journal of Statistics, 36(1), 75--84. White, G. (2005) Software Developed by Department of Fishery and Wildlife Biology and Colorado Coop. Fish and Wildlife Unit, Colorado State University. http://www.warnercnr.colostate.edu/~gwhite/software.html. White, G. and Burnham, K.P. (1999) Program Mark: Survival Estimation from Populations of Marked Animals. Bird Study, 46 (Supplement), 120--138.

Examples

data(hare)
hare.desc<-descriptive(hare)
hare.desc
plot(hare.desc)

data(catb)
catb.desc<-descriptive(catb,dfreq=TRUE,dtype="nbcap",t=11)
plot(catb.desc)